This Training Grant, currently in its 35th year of funding, represents the primary support for graduate students in the Immunology Training Program at the University of Chicago. The Program is conducted in a diverse environment where the basic biological sciences and the medical school and clinical programs are integrated within the same Division in a single Campus in Hyde Park, Chicago, IL. It is embodied by the Committee on Immunology, an interdisciplinary and interdepartmental academic unit, which includes some of the most distinguished and productive faculty in various Departments. The faculty is composed of 31 trainers selected for their outstanding research and training record, their well-funded laboratory and their dynamic involvement in all aspects of the Program. They form a diverse, age and gender-balanced group, whose research spans a broad spectrum of basic as well as translational Immunology, including modern or emerging areas such as live imaging, genomics and systems biology, microbiome studies, chemical biology, molecular engineering and human immunology. Predoctoral students receive advanced training in Immunology through a formal series of courses, including a core basic curriculum and electives from a wide range of scientific disciplines, and laboratory rotations. The comprehensive training also includes a weekly Journal Club, Work-in-Progress and Seminar Series, and an annual two-day Retreat. All predocs and postdocs receive training in responsible conduct of research. Career development is enhanced through a dedicated career seminar series, formal training for grantsmanship, and partnership with UChicago Booth School of Business to develop biomedical entrepreneurship. There is strong institutional support, shown by the major allocation of new space, the regroupment of faculty in a new Immunology Hub at the center of the renovated campus, the sustained financial and administrative support from the Biomedical Science Division. New strength is drawn from the recruitment of immunology training faculty in emerging areas such as microbiome studies and in physical sciences, such as chemical biology, computational biology and molecular engineering, with a proven record of interdisciplinary collaborations. The Program is continuously and rigorously evaluated with respect to organization, leadership, objectives and outcomes. With a world-renowned group of dynamic faculty and a large pool of exceptionally qualified applicants, this is one of the best and most competitive training program in the country, as shown by the high retention and completion rates of our trainees, which include many underrepresented minority students, their impressive publication rate (average of 6 publications/per trainee, including in highest impact journals such as Nature, Science, Cell) and their success in securing independent scientific careers with many tenure-track academic positions. Based on this track record of success and growth, continued support is requested with an increment of two slots.